Thin film transistor liquid crystal display, or TFT-LCD for short, is commonly used due to its characteristics such as quick response, low driving voltage, excellent gray scale display, and so on. A TFT-LCD crystal panel comprises an array substrate and a color film substrate disposed opposite with each other, and a liquid crystal layer filled between the array substrate and the color film substrate. According to the difference in directions of driving liquid crystal electric filed, liquid crystal display devices may be classified into multiple modes including Twisted Nematic (TN) mode, Vertical Alignment (VA) mode, In-Plane Switching (IPS) mode and Advanced Super Dimension Switch (ADS) mode and so on. In the Twisted Nematic (TN) mode, liquid crystal is twisted as being applied with a voltage, and the extent to which liquid crystal is twisted is controlled by controlling the voltage so as to achieve the purpose of modulating transmittance (displaying gray scale). Since the optical anisotropy of liquid crystal molecules results in a defect of narrow viewing angle of a screen, the prior art proposes a liquid crystal driving mode capable of broadening the viewing angle, that is, the In-Plane Switching (IPS for short) mode. A liquid crystal display using such mode is also called transverse electric field mode thin film transistor liquid crystal display (IPS type TFT-LCD for short).
A structure of electrodes in a conventional IPS type TFT-LCD panel is illustrated in FIG. 1, in which both pixel electrodes 1 and common electrodes 2 are formed on the same surface of a lower substrate 4 (array substrate) of the TFT-LCD substrate, and no electrode is formed on an upper substrate 3 (color film substrate). After voltages are applied, since the pixel electrodes 1 and the common electrodes 2 are in the same plane, horizontal electric fields are formed in regions between the pixel electrodes 1 and the common electrodes 2, however, for regions right above the pixel electrodes 1 and the common electrodes 2, no horizontal electric field is formed therein, and accordingly, liquid crystal molecules in the regions cannot be rotated, such that lights cannot transmit through the regions, resulting in low transmittance of the liquid crystal panel.